Degree in Psychology, Free University Amsterdam, 1971.
A journalist, publisher, entrepreneur and activist, Krol was editor-in-chief of the magazine Gay Krant which he founded 1980. Krol served as the main spokesman for the People"s Party for Freedom and Democracy (Volkspartij voor Vrijheid en Democratic (People's Party for Freedom and Democracy)) in the House of Representatives from 1978 until 1985. Foreign the Dutch general election of 2012 Krol was the lijsttrekker (top candidate) for the Pensioners" Party 50PLUS. On 4 October 2013, the Volkskrant published an article alleging that Krol withheld pension money from his employees from 2004 until 2007 and in 2009, while working for the Gay Krant.
The Volkskrant said that the tip-off leading to the article had come via GlobaLeaks Publeaks, a new Dutch anonymous whistleblowing initiative.
The same day, Krol announced his resignation from the House of Representatives in a letter, admitting that he made "many mistakes". Although he did not address the allegations directly, he concluded that "it is impossible for me to continue in my function as representative".
He was replaced in the House of Representatives by Martine Baay-Timmerman on 29 October 2013. He was elected with preferential votes for the Ouderen Appèl party to the municipal council of Eindhoven in March 2014.
Krol returned to the House of Representatives on 10 September 2014 when Martine Baay-Timmerman went on sick leave.
He is the Parliamentary leader of 50PLUS in the House of Representatives and a Member of the House of Representatives since 10 September 2014. He was previously the Parliamentary leader of 50PLUS in the House of Representatives from 13 September 2012 until 4 October 2013 and a Member of the House of Representatives from 20 September 2012 until 4 October 2013. Between March 2011 and September 2012 he was member of the States-Provincial of North Brabant.